Method and device of dynamically configuring linear density and blending ratio of yarn by three-ingredient asynchronous/synchronous drafted

ABSTRACT

The invention discloses a method of dynamically configuring linear density and blending ratio of yarn by three-ingredient asynchronous/synchronous drafted, comprising: a drafting and twisting system, which includes a first stage drafting unit, a successive second stage drafting unit and an integrating and twisting unit. The first stage drafting unit includes a combination of back rollers and a middle roller. The second stage drafting unit includes a front roller and the middle roller. Blending proportion and linear densities of three ingredients are dynamically adjusted by the first stage asynchronous drafting mechanism, and reference linear density is adjusted by the second stage synchronous drafting mechanism. The invention can not only accurately control linear density change, but also accurately control a color change of the yarn. Further, the rotation rate of the middle roller is constant, ensuring a reproducibility of the patterns and colors of the yarn with a changing linear density.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase entry application of InternationalApplication No. PCT/CN2015/085269, filed on Jul. 28, 2015, which isbased upon and claims priority to NO. CN201510140910.4, filed on Mar.27, 2015, claims another priority to NO. CN201510140466.6, filed on Mar.27, 2015, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

The invention relates to a ring spinning filed of a textile industry,and particularly relates to a method and device of dynamicallyconfiguring a linear density and a blending ratio of a yarn bythree-ingredient asynchronous/synchronous drafted.

BACKGROUND

Yarn is a long and thin fiber assembly formed by orienting in paralleland twisting of fiber. The characteristic parameters generally includefineness (linear density), twist, blending ratio (color blending ratio),etc. The characteristic parameters are important features which shouldbe controlled during a forming process.

The yarn can be divided into four categories:

(1) yarn with a constant linear density and a variable blending ratio,such as a color yarn of constant liner density, with a gradient orsegmented color;

(2) yarn with a constant blending ratio and variable linear density,such as a slub yarn, a dotted yarn, etc.;

(3) yarn with a variable linear density and blending ratio, such assegmented a color slub yarn, a segmented color dotted yarn, etc.;

(4) blended yarn or mixed color yarn mixed at any rate, with a constantlinear density and blending ratio.

The development of yarn processing technology mainly relates to theproblems of special yarns. The existing spinning technology and thepatent applications fail to guide the spinning production of the abovefour types of yarns, challenging the existing spinning theories.Specifically, it is analyzed as follows:

(1) yarn with a constant linear density and a variable blending ratio(color blending ratio)

The yarn with a constant linear density and a variable blending ratio(color blending ratio) can be assumed as a color yarn of constant linerdensity, with a gradient or segmented color. No existing patentapplication is related to this type of yarn.

(2) yarn with a constant blending ratio and variable linear density

The yarn with a constant blending ratio and variable linear density, canbe such as a slub yarn, a dotted yarn, etc. The existing method ofmanufacturing the ring spun yarn with a variable linear densitycomprises feeding one roving yarn each to the middle roller and backroller, and discontinuously spinning to manufacture the yarns withvariable linear density by uneven feeding from the back roller. Forexample, a patent entitled “a discontinuous spinning process and yarnsthereof” (ZL01126398.9), comprising: feeding an auxiliary fiber strand Bfrom the back roller; unevenly drafting it via the middle roller andback roller; integrating with another main fiber strand A fed from themiddle roller, and entering into the drafting area; drafting them by thefront roller and middle roller, and outputting from the jaw of the frontroller; entering into the twisting area to be twisted and form yarns.Because the auxiliary fiber strand is fed from the back rollerintermittently and integrates with the main fiber strand, under theinfluence of the front area main drafting ratio, the main fiber strandis evenly attenuated to a certain linear density, and the auxiliaryfiber strand is attached to the main fiber strand to form adiscontinuous and uneven linear density distribution. By controlling thefluctuation quantity of the uneven feeding from the back roller,different effects such as a dotted yarn, a slub yarn, etc. are obtainedfinally on the yarn. The deficiencies of this method are that the mainand auxiliary fiber strands cannot be exchanged and a range of slubthickness is limited.

(3) yarn with a variable linear density and blending ratio

No existing patent application relates to this type of yarn.

(4) blended yarn or mixed color yarn mixed at any rate, with a constantlinear density and blending ratio

The blended yarn or mixed color yarn mixed at any rate, with a constantlinear density and blending ratio, are disclosed. The current methodcomprises blending two or more than two different ingredients to obtaina roving yarn at a certain blending ratio, by fore-spinning process,then spinning the roving yarn to form a spun yarn by spinning process toobtain a yarn with a constant linear density and a blending ratio.Usually spinning processes can only achieve several conventionalproportions, such as 50:50, 65:35, 60:40. The deficiencies are that theycannot be blended at any rate and two or more than two fibers cannot beblended at any rate in a single step.

SUMMARY OF THE INVENTION

To solve the above problems, the objective of this invention is todisclose a process of providing three-ingredientasynchronous/synchronous two-stage drafting fiber strands, and thenintegrating and twisting to form a yarn. The linear density and blendingratio of a ring spun yarn can be adjusted arbitrarily. The invention canadjust the linear density and blending ratio of the yarn at the sametime to produce the above four types of yarns, overcoming the limitationof being unable to adjust characteristic parameters of a yarn on line.

To achieve the above objectives, the invention discloses a method ofdynamically configuring linear density and blending ratio of yarn bythree-ingredient asynchronous drafting, comprising:

1) An actuating mechanism mainly includes a three-ingredientasynchronous/synchronous two-stage drafting mechanism, a twistingmechanism and a winding mechanism. The three-ingredientasynchronous/synchronous two-stage drafting mechanism includes a firststage asynchronous drafting unit and a successive second stagesynchronous drafting unit;

2) The first stage asynchronous drafting unit includes a combination ofback rollers and a middle roller. The combination of back rollers hasthree rotational degrees of freedom and includes a first back roller, asecond back roller, a third back roller, which are set abreast on a sameback roller shaft. A first back roller, a second back roller, a thirdback roller move at the speeds V_(h1), V_(h2), and V_(h3) respectively.The middle roller rotates at the speed V_(z). The second stagesynchronous drafting unit includes a front roller and the middle roller.The front roller rotates at the surface linear speed V_(q).

Assuming the linear densities of a first roving yarn ingredient, asecond roving yarn ingredient, a third roving yarn ingredient drafted bya first back roller, a second back roller, a third back roller arerespectively ρ₁, ρ₂, and ρ₃, the linear density of the yarn Y draftedand twisted by the front roller is ρ_(y).

$\begin{matrix}{\rho_{y} = {\frac{1}{V_{q}}\left( {{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}} \right)}} & (1)\end{matrix}$

The blending ratios of the first roving yarn ingredient, the secondroving yarn ingredient, and the third roving yarn ingredient arerespectively k₁, k₂, and k₃.

$k_{1} = {\frac{\rho_{1}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{1}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{1}*V_{h\; 1}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{2} = {\frac{\rho_{2}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{2}*V_{h\; 2}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{3} = {\frac{\rho_{3}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{3}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{3}*V_{h\; 3}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$

3) Keeping the ratio of linear speeds of the front roller and the middleroller V_(q)/V_(z) constant, the speeds of the front roller and themiddle roller depend on reference linear density of the yarn;

4) The linear density of yarn Y or/and blending ratio can be dynamicallyadjusted on line, by adjusting the rotation rates of the first backroller, the second back roller.

Further, according to the changes of the blending ratio K of the yarn Ywith time t, and the changes of the linear density ρ_(y) of the yarn Ywith the time t, the changes of the surface linear speeds of a firstback roller, a second back roller, a third back roller are derived. Theblending ratios of the first roving yarn ingredient, the second rovingyarn ingredient, the third roving yarn ingredient are set respectivelyas k₁, k₂, and k₃. The ratios of blending ratios of the yarn Y arerespectively K₁, and K₂.

$K_{1} = {\frac{k_{1}}{k_{2}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{2}V_{h\; 3}}}$$K_{2} = {\frac{k_{1}}{k_{3}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{3}V_{h\; 3}}}$

Linear density of yarn Y is

$\rho_{y} = \frac{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}{V_{q}}$

Then a surface linear speed of the back roller 1:

$V_{h\; 1} = \frac{\rho_{y}V_{q}}{\rho_{1}\left( {1 + \frac{1}{K_{1}} + \frac{1}{K_{2}}} \right)}$

a surface linear speed of the back roller 2:

$V_{h\; 2} = \frac{\rho_{y}V_{q}}{\rho_{2}\left( {1 + K_{1} + \frac{K_{1}}{K_{2}}} \right)}$

a surface linear speed of the back roller 3:

$V_{h\; 3} = \frac{\rho_{y}V_{q}}{\rho_{3}\left( {1 + K_{2} + \frac{K_{2}}{K_{1}}} \right)}$

wherein ρ₁, ρ₂, and ρ₃ are constants, and K_(i) and ρ_(y) are functionschanging with time t.

Further, let ρ₁=ρ₂=ρ₃=ρ, then:

1) change the speed of any one of the first back roller, the second backroller, and the third back roller, and keep the speeds of the other twobacker rollers unchanged. The yarn ingredient and the linear densitythereof of the yarn Y drafted by this back roller change accordingly.The linear density ρ′_(y) of the yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 2}}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 1}}} \right)}}$

wherein Δρ_(y) is a linear density change of the yarn, ΔV_(h1), ΔV_(h2)and ΔV_(h3) is a speed change of the first back roller, the second backroller, and the third back roller respectively.

2) change the speeds of any two back rollers of the first back roller,the second back roller, and the third back roller, and keep the speedsof the other backer rollers unchanged. The yarn ingredients of the yarnY drafted by these any two back rollers and the linear densities thereofchange accordingly. The linear density ρ′_(y) of yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack}}$

3) change the speeds of three back rollers of the first back roller, thesecond back roller, and the third back roller simultaneously. The yarningredients of the yarn Y drafted by these any three back rollers andthe linear densities thereof change accordingly. The linear densityρ′_(y) of the yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack}}$

further, change the speeds of the first back roller, the second backroller, and the third back roller, and make the speed of any of backrollers equal to zero, while the speeds of the other two backer rollersunequal to zero. The yarn ingredient of the yarn Y drafted by the anyone of back rollers is thus discontinuous, while the other two yarningredients are continuous. The linear density ρ′_(y) of yarn Y isadjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$

wherein T₁ and T₂ are time points, and t is a time variable.

Further, change the speeds of the first back roller, the second backroller, and the third back roller, make the speeds of any two backrollers equal to zero successively, while the speeds of the other onebacker rollers unequal to zero. The yarn ingredients of the yarn Ydrafted by the any two back rollers are thus discontinuous, while theother yarn ingredients are continuous. The linear density ρ′_(y) of theyarn Y is adjusted as:

1) When the first back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$

wherein T₃ is time points, and T₁≤T₂≤T₃

2) When the second back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$

3) When the third back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{2} \leq t \leq T_{3}} \right).}}}}$

Further change the speeds of the first back roller, the second backroller, and the third back roller, make the speeds of any two backrollers equal to zero simultaneously, while the speeds of the other onebacker rollers unequal to zero. The yarn ingredients of the yarn Ydrafted by the any two back rollers are thus discontinuous, while theother one yarn ingredients are continuous. The linear density ρ′_(y) ofthe yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\rho}_{y}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{1} \leq t \leq T_{2}} \right).}}}}$

Further, change the speeds of the first back roller, the second backroller, and the third back roller, and keep

V_(h1)*ρ₁+V_(h2)*ρ₂+V_(h3)*ρ₃=constant and ρ₁=ρ₂=ρ₃=ρ,

then the linear density of the yarn Y is thus fixed while the blendingratios of the ingredients thereof change; the blending ratios of thefirst yarn ingredient, the second yarn ingredient, and the third yarningredient are k₁, k₂, k₃.

$k_{1} = \frac{V_{h\; 1} + {\Delta\; V_{h\; 1}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{2} = \frac{V_{h\; 2} + {\Delta\; V_{h\; 2}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{3} = \frac{V_{h\; 3} + {\Delta\; V_{h\; 3}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$

Further, according to the set blending ratio and/or linear density,divide the yarn Y into n segments. The linear density and blending ratioof each segment of the yarn Y are the same, while the linear densitiesand blending ratios of the adjacent segments are different. Whendrafting the segment i of the yarn Y, the linear speeds of a first backroller, a second back roller, a third back roller are V_(h1i), V_(h2i),V_(h3i), wherein i∈(1, 2, . . . , n). The first roving yarn ingredient,the second roving yarn ingredient, the third roving yarn ingredientingredient are two-stage drafted and twisted to form segment i of theyarn Y, and the blending ratios k_(1i), k_(2i) and k_(3i) thereof areexpressed as below:

$\begin{matrix}{k_{1i} = \frac{\rho_{1}*V_{h\; 1i}}{{\rho_{1}*V_{h\; 1i}} + {\rho_{2}*V_{h\; 2i}} + {\rho_{3}*V_{h\; 3i}}}} & (2) \\{k_{2i} = \frac{\rho_{2}*V_{h\; 2i}}{{\rho_{1}*V_{h\; 1i}} + {\rho_{2}*V_{h\; 2i}} + {\rho_{3}*V_{h\; 3i}}}} & (3) \\{k_{3i} = \frac{\rho_{3}*V_{h\; 3i}}{{\rho_{1}*V_{h\; 1i}} + {\rho_{2}*V_{h\; 2i}} + {\rho_{3}*V_{h\; 3i}}}} & (4)\end{matrix}$

the linear density of segment i of yarn Y is:

$\begin{matrix}{\rho_{y\; i} = {{\frac{V_{z}}{V_{q}}*\left( {{\frac{V_{h\; 1i}}{V_{z}}*\rho_{1}} + {\frac{V_{h\; 2i}}{V_{z}}\rho_{2}} + {\frac{V_{h\; 3i}}{V_{z}}\rho_{3}}} \right)} = {\frac{1}{e_{q}}*\left( {{\frac{V_{h\; 1i}}{V_{z}}*\rho_{1}} + {\frac{V_{h\; 2i}}{V_{z}}\rho_{2}} + {\frac{V_{h\; 3i}}{V_{z}}\rho_{3}}} \right)}}} & (5)\end{matrix}$

Wherein

$e_{q} = \frac{V_{q}}{V_{z}}$is the two-stage drafting ratio;

(1) Take the segment with the lowest density as a reference segment,whose reference linear density is ρ₀. The reference linear speeds of thefirst back roller, the second back roller, the third back roller forthis segment are respectively V_(h10), V_(h20), V_(h30); and thereference blending ratios of the first roving yarn ingredient, thesecond roving yarn ingredient, the third roving yarn ingredient for thissegment are respectively k₁₀, k₂₀, k₃₀,

Keep the linear speed of the middle roller constant, andV _(z) =V _(h10) +V _(h20) +V _(h30)  (6);

(2) also keep two-stage drafting ratio

$e_{q} = \frac{V_{q}}{V_{z}}$constant; wherein the reference linear speeds of the first back roller,the second back roller, the third back roller for this segment arerespectively V_(h10), V_(h20), V_(h30), which can be predeterminedaccording to the material, reference linear density ρ₀ and referenceblending ratios k₁₀, k₂₀, k₃₀ of the first roving yarn ingredient, thesecond roving yarn ingredient, the third roving yarn ingredient.

(3) When the segment i of the yarn Y is drafted and blended, on thepremise of known set linear density ρ_(yi) and blending ratios k_(1i),k_(2i), k_(3i), the linear speeds V_(h1i), V_(h2i), V_(h3i), of thefirst back roller, the second back roller, the third back roller arecalculated according to Equations (2)-(6);

(4) Based on the reference linear speeds V_(h10), V_(h20), V_(h30) forthe reference segment, increase or decrease the rotation rates of thefirst back roller, the second back roller, the third back roller todynamically adjust the linear density or/and blending ratio for thesegment i of the yarn Y.

Further, let ρ₁=ρ₂=ρ₃=ρ

then Equation (5) can be simplified as

$\begin{matrix}{\rho_{yi} = {\frac{\rho}{e_{q}}*{\frac{V_{h\; 1i} + V_{h\; 2i} + V_{h\; 3i}}{V_{z}}.}}} & (7)\end{matrix}$

According to Equations (2)-(4) and (6)-(7), the linear speeds V_(h1i),V_(h2i), V_(h3i) of the first back roller, the second back roller, thethird back roller are calculated; based on the reference linear speedsV_(h10), V_(h20), V_(h30), the rotation rates of the first back roller,the second back roller, the third back roller are increased or decreasedto reach the preset linear density and blending ratio for the segment iof yarn Y.

Further, at the moment of switching the segment i−1 to the segment i ofyarn Y, let the linear density of the yarn Y increase by dynamicincrement Δρ_(yi), i.e., thickness change Δρ_(yi), on the basis ofreference linear density; and thus the first back roller, the secondback roller, the third back roller have corresponding increments on thebasis of the reference linear speed, i.e., when(V_(h10)+V_(h20)+V_(h30))→(V_(h10)+ΔV_(h1i)+V_(h20)+ΔV_(h2i)V_(h30)+ΔV_(h3i)), the linear density increment of yarn Y is:

${\Delta\rho}_{yi} = {\frac{\rho}{e_{q}*V_{z}}*\left( {{\Delta\; V_{h\; 1i}} + {\Delta\; V_{h\; 2i}} + {\Delta\; V_{h\; 3i}}} \right)\text{;}}$

Then the linear density ρ_(yi) of the yarn Y is expressed as

$\begin{matrix}{\rho_{yi} = {{\rho_{y\; 0} + {\Delta\rho}_{yi}} = {\rho_{y\; 0} + {\frac{{\Delta\; V_{h\; 1i}} + {\Delta\; V_{h\; 2i}} + {\Delta\; V_{h\; 3i}}}{V_{z}}*{\frac{\rho}{e_{q}}.}}}}} & (8)\end{matrix}$

Let ΔV₁=ΔV_(h1i)+ΔV_(h2i)+ΔV_(h3i),

then Equation (8) is simplified as:

$\begin{matrix}{\rho_{yi} = {\rho_{y\; 0} + {\frac{\Delta\; V_{1}}{V_{z}}*{\frac{\rho}{e_{q}}.}}}} & (9)\end{matrix}$

The linear density of yarn Y can be adjusted by controlling the sum ofthe linear speed increments ΔV_(i) of the first back roller, the secondback roller, the third back roller.

Further, let ρ₁=ρ₂=ρ₃=ρ at the moment of switching the segment i−1 tothe segment i of the yarn Y, the blending ratios of the yarn YinEquations (2)-(4) can be simplified as:

$\begin{matrix}{k_{1i} = \frac{V_{h\; 10} + {\Delta\; V_{h\; 1i}}}{V_{z} + {\Delta\; V_{i}}}} & (10) \\{k_{2i} = \frac{V_{h\; 20} + {\Delta\; V_{h\; 2i}}}{V_{z} + {\Delta\; V_{i}}}} & (11) \\{k_{3i} = \frac{V_{h\; 30} + {\Delta\; V_{h\; 3i}}}{V_{z} + {\Delta\; V_{i}}}} & (12)\end{matrix}$

The blending ratios of the yarn Y can be adjusted by controlling thelinear speed increments of the first back roller, the second backroller, the third back roller;

whereinΔV _(h1i) =k _(1i)*(V _(Z) +ΔV _(i))−V _(h10)ΔV _(h2i) =k _(2i)*(V _(Z) +ΔV _(i))−V _(h20)ΔV _(h3i) =k _(3i)*(V _(Z) +ΔV _(i))−V _(h30).

Further, let V_(h1i)*ρ₁V+_(h2i)*ρ₂+V_(h3i)*ρ₃=H and H is a constant,then ΔV_(i) is constantly equal to zero, and thus the linear density isunchanged when the blending ratios of the yarn Y are adjusted.

Further, let any one to two of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equal tozero, while the remaining ones are not zero, then the one to two rovingyarn ingredients can be changed while the other roving yarn ingredientsare unchanged. The adjusted blending ratios are:

$k_{ki} = \frac{V_{{hk}\; 0} + {\Delta\; V_{hki}}}{V_{z} + {\Delta\; V_{i}}}$$K_{ji} = \frac{V_{{hj}\; 0}}{V_{z} + {\Delta\; V_{i}}}$

wherein k, j∈(1, 2, 3), and k≠j.

Further, let none of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equal to zero, thenthe proportion of the three roving yarn ingredients in the yarn Y may bechanged.

Further, let any one to two of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equal tozero, while the remaining ones are not zero, then the one to two rovingyarn ingredients of the segment i of the yarn Y may be discontinuous.

A device for configuring a linear density and a blending ratio of a yarnby three-ingredient asynchronous/synchronous drafted, comprises acontrol system and an actuating mechanism. The actuating mechanismincludes three-ingredient asynchronous/synchronous two-stage draftingmechanism, a twisting mechanism and a winding mechanism. The two-stagedrafting mechanism includes a first stage drafting unit and a secondstage drafting unit; the first stage drafting unit includes acombination of back rollers and a middle roller. The combination of backrollers has three rotational degrees of freedom and includes a firstback roller, a second back roller, a third back roller, which are setabreast on a same back roller shaft. The three back rollers are setadjacently and the driving mechanisms thereof are set on both sides ofthe three back rollers. The second stage drafting unit includes a frontroller and the middle roller.

Further, the control system mainly includes a PLC programmablecontroller, a servo driver, a servo motor, etc.

Further, any of the three back rollers is fixedly set on the back rollershaft. The other two back rollers are respectively set on the backroller shaft, and independently rotatable with each other.

Further, during the process of drafting, the speed of the middle rolleris fixed and no more than the sum of the speeds of the first backroller, the second back roller, the third back roller.

The dotted yarn and slub yarn produced by the method and device of theinvention are more even and accurate in color mixing. Further, therotation rate of the middle roller is constant, ensuring the stableblending effect. The color difference of the yarn from different batchesis not obvious. The contrast about technical effects between theinvention and the prior art is showed in the following table.

TABLE 1 The contrast about technical effects between the invention andthe prior art Dot yarn Slub yarn Linear pattern linear density densityColor- errors adjustment adjustment blending (/100 m) error rate errorrate evenness prior art 7-8 10-12% 11-13% level 2-3 the invention 1-2 1-3%  1-3% level 1

Therefore, the invention is very effective.

The method of the invention changes the traditional three-ingredientfront and back areas synchronous drafting to three-ingredient separateasynchronous drafting (referred to as first stage asynchronous drafting)and three-ingredient integrated synchronous drafting (referred to assecond stage synchronous drafting). The blending proportion of the threeingredients and linear density of the yarn are dynamically adjusted bythe first stage separate asynchronous drafting, and the reference lineardensity of the yarn is adjusted by the second stage synchronousdrafting. The linear density and the blending ratio of the yarn can bedynamically adjusted online by the three-ingredient separate/integratedasynchronous/synchronous two-stage drafting, combined with the spinningdevice and process of the twisting, which breaks through the threebottlenecks existing in the slub yarn spinning process of the prior art.The three bottlenecks are: 1. only the linear density can be adjustedwhile the blending ratio (color change) cannot be adjusted; 2.monotonous pattern of the slub yarn; 3. poor reproducibility of the slubyarn pattern.

Calculations for the Processing Parameters of Three-IngredientSeparate/Integrated Asynchronous/Synchronous Two-Stage Drafting CoaxialTwisting Spinning System

According to the drafting theory, the drafting ratio of the first stagedrafting is:

$\begin{matrix}{e_{h\; 1} = {\frac{V_{z}}{V_{h\; 1}} = \frac{\rho_{1}}{\rho_{1}^{\prime}}}} & (1) \\{e_{h\; 2} = {\frac{V_{z}}{V_{h\; 2}} = \frac{\rho_{2}}{\rho_{2}^{\prime}}}} & (2) \\{e_{h\; 3} = {\frac{V_{z}}{V_{h\; 3}} = \frac{\rho_{3}}{\rho_{2}^{\prime}}}} & (3)\end{matrix}$

The equivalent drafting ratio of the first stage drafting is:

$\begin{matrix}{{\overset{\_}{e}}_{h} = \frac{{\rho_{1 +}\rho_{2}} + \rho_{3}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}}} & (4)\end{matrix}$

The drafting ratio of the second stage drafting is:

$\begin{matrix}{e_{q} = {\frac{V_{q}}{V_{z}} = {\frac{\rho_{1}^{\prime}}{\rho_{1}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{2}^{''}} = {\frac{\rho_{3}^{\prime}}{\rho_{3}^{''}} = \frac{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}}}}}}} & (5)\end{matrix}$

The total equivalent drafting ratio e is:

$\begin{matrix}{\overset{\_}{e} = {\frac{\rho_{1} + \rho_{2} + \rho_{3}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {{\overset{\_}{e}}_{h}*e_{q}}}} & (6)\end{matrix}$

The total equivalent drafting ratio ē is a significant parameter in thespinning process, which is the product of front area drafting ratio andback area drafting ratio.

According to the established spinning model of the invention, the threeroving yarns ρ₁, ρ₂ and ρ₃ are asynchronously drafted in the back areaand synchronously drafted in the front area and then are integrated andtwisted to form a yarn, the blending ratios thereof k₁, k₂, k₃ can beexpressed as follows:

$\begin{matrix}{k_{1} = {\frac{\rho_{1}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{1}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{1}*V_{h\; 1}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}} & (7) \\{k_{2} = {\frac{\rho_{2}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{2}*V_{h\; 2}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}} & (8) \\{k_{3} = {\frac{\rho_{2}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{3}*V_{h\; 3}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}} & (9)\end{matrix}$

As known from the Equations (7), (8), (9) the blending ratios of thethree ingredients in the yarn is related to the surface rotation ratesV_(h1), V_(h2), V_(h3) of the back rollers and the linear densities ρ₁,ρ₂, ρ₃ of the three roving yarns. Generally, ρ₁, ρ₂, ρ₃ are constant andirrelevant to the time, while V_(h1), V_(h2), V_(h3) are related to thespeed of the main shaft. Because the main shaft speed has a bearing onthe spinner production, different main shaft speeds are adopted fordifferent materials and product specifications in different enterprises.As such, even though ρ₁, ρ₂, ρ₃ of the roving yarns are constant, theblending ratios determined by Equations (6), (7) change due to the speedchange of the main shaft, which results in the changes of V_(h1),V_(h2), V_(h3) rendering the blending ratios uncertain.

In the same way, the three roving yarns are two-stage drafted,integrated and twisted to form a yarn with the following linear density:

$\mspace{79mu}{\rho_{y} = {\frac{\rho_{1} + \rho_{2} + \rho_{3}}{\overset{\_}{e}} = {\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}}}}$$\rho_{y} = {{{\frac{V_{z}}{V_{q}}*\rho_{1}^{\prime}} + {\frac{V_{z}}{V_{q}}*\rho_{2}^{\prime}} + {\frac{V_{z}}{V_{q}}*\rho_{3}^{\prime}}} = {{\frac{V_{z}}{V_{q}}*\frac{V_{{h\; 1}\;}}{V_{z}}*\rho_{1}} + {\frac{V_{2}}{V_{q}}*\frac{V_{h\; 2}}{V_{z}}\rho_{2}} + {\frac{V_{2}}{V_{q}}*\frac{V_{h\; 3}}{V_{z}}\rho_{3}}}}$

and then the linear density of the yarn is:

$\begin{matrix}{\rho_{y} = {\frac{1}{V_{q}}\left( {{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}} \right)}} & (10)\end{matrix}$

As known from Equation (10), the linear density of the yarn is relatedto the speed V_(h1), V_(h2), V_(h3) of the combination of back rollersand the linear densities ρ₁, ρ₂, ρ₃ of the three roving yarns.Generally, ρ₁, ρ₂, ρ₃ are constant and irrelevant to the time whileV_(h1), V_(h2), V_(h3) are related to the main shaft speed set by thespinning machine. Because the main shaft speed has a bearing on theproduction of the spinning machine, different main shaft speeds would beadopted when spinning the different materials with different productspecifications in different enterprises. As such, for the linear densitydetermined by Equation (8), even though ρ₁, ρ₂, ρ₃ of the three rovingyarns remain unchanged, V_(h1), V_(h2), V_(h3) would change with themain shaft speed, rendering the linear density uncertain.

From Equation (1):

$\rho_{1}^{\prime} = {\frac{V_{h\; 2}}{V_{2}}*\rho_{1}}$

From Equation (2):

$\rho_{2}^{\prime} = {\frac{V_{h\; 2}}{V_{2}}*\rho_{2}}$

From Equation (3):

$\rho_{3}^{\prime} = {\frac{V_{h\; 2}}{V_{2}}*\rho_{3}}$

$\begin{matrix}{{\therefore{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}}} = \frac{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}{V_{z}}} & (11)\end{matrix}$

Equation (9) is substituted in Equation (3) and then solved for theequivalent drafting ratio ē_(h):

$\begin{matrix}{{\overset{\_}{e}}_{h} = {\frac{\rho_{1} + \rho_{2} + \rho_{3}}{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}*V_{z}}} & (12)\end{matrix}$

Equation (10) is substituted in Equation (5) and then solved for thetotal equivalent drafting ratio ē:

$\begin{matrix}{{\overset{\_}{e} = {\frac{\rho_{1} + \rho_{2} + \rho_{3}}{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{3}} + {V_{h\; 3}*\rho_{3}}}*V_{z}*\frac{V_{q}}{V_{z}}}}{\overset{\_}{e} = {\frac{\rho_{1} + \rho_{2} + \rho_{3}}{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}*V_{q}}}} & (13)\end{matrix}$

To negate the changes caused by the different main shaft speeds, thelimited condition is provided as follows:ρ₁=ρ₂=ρ₃=ρ  (14)

Equation (14) is substituted in Equation (9):

$\begin{matrix}{{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = {\rho*\frac{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}{V_{z}}}} & (15)\end{matrix}$

Equations (12), (13) are substituted in Equation (10):

$\begin{matrix}{{\overset{\_}{e}}_{h} = \frac{V_{z}}{\frac{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}{3}}} & (16)\end{matrix}$

Equations (14) is substituted in Equation (5):

$\begin{matrix}{\overset{\_}{e} = {{{\overset{\_}{e}}_{h}*e_{q}} = \frac{V_{q}}{\frac{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}{3}}}} & (17)\end{matrix}$

Equations (15), (16), (17) are substituted in Equations (7), (8), (9):

$\begin{matrix}{k_{1} = {\frac{V_{h\; 1}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}} = {\frac{V_{z}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}*\frac{1}{e_{h\; 1}}}}} & (18) \\{k_{2} = {\frac{V_{h\; 2}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}} = {\frac{V_{z}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}*\frac{1}{e_{h\; 2}}}}} & (19) \\{k_{3} = {\frac{V_{h\; 3}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}} = {\frac{V_{z}}{V_{h\; 1} + V_{h\; 2} + V_{h\; 3}}*\frac{1}{e_{h\; 3}}}}} & (20)\end{matrix}$

Assuming ρ₁=ρ₂=ρ₃=ρ, and adjusting the speeds of the first back roller,the second back roller and the third back roller making sure thatV_(h1)+V_(h2)+V_(h3)=V_(Z),

then Equations (18), (19), (20) are changed as:

$k_{1} = {\frac{V_{h\; 1}}{V_{z}} = \frac{1}{e_{h\; 1}}}$$k_{2} = {\frac{V_{h\; 2}}{V_{z}} = \frac{1}{e_{h\; 2}}}$$k_{3} = {\frac{V_{h\; 3}}{V_{z}} = \frac{1}{e_{h\; 3}}}$

The blending ratios of the three ingredients ρ₁, ρ₂, ρ₃ in the yarn areequal to the inverses of their respective drafting ratios.

$e_{h\; 1} = {\frac{V_{z}}{V_{h\; 1}} = \frac{1}{k_{1}}}$$e_{h\; 2} = {\frac{V_{z}}{V_{h\; 2}} = \frac{1}{k_{2}}}$$e_{h\; 3} = {\frac{V_{z}}{V_{h\; 3}} = \frac{1}{k_{3}}}$

For example, assuming:

k₁=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1

k₂=0.7, 0.6, 0.5, 0.4, 0, 3, 0, 2, 0.1, 0, 0.1, 0.1, 0

k₃=0.3, 0.3, 0.3, 0.3, 0.3, 0.3, 0.3, 0, 3, 0.1, 0, 0

Then e_(h1), e_(h2) and e_(h3) can be calculated respectively, as showedin Table 2.

TABLE 2 Blend ratio and first-stage drafting ratio k₁ 0   0.1 0.2 0.30.4 0.5 0.6 0.7 0.8 0.9 1 e_(h1) X 10   5   10/3 10/4 10/5 10/6 10/710/8 10/9 1 k₂ 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0   0.1 0.1 0 e_(h2) 10/710/6 10/5 10/4 10/3 5   10   X 10   10   X k₃ 0.3 0.3 0.3 0.3 0.3 0.30.3 0.3 0.1 0   0 e_(h3) 10/3 10/3 10/3 10/3 10/3 10/3 10/3 10/3 10   XX

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a principle schematic diagram of the two-stage draftingspinning device;

FIG. 2 is a structural schematic diagram of a combination of backrollers;

FIG. 3 is a structural side view of the two-stage drafting spinningdevice;

FIG. 4 is a yarn route of the two-stage drafting in an embodiment;

FIG. 5 is a structural schematic diagram of a control system.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the invention are described as below, in combinationwith the accompanying drawings.

Embodiment 1

As demonstrated by FIG. 1-5, a method of dynamically configuring lineardensity and blending ratio of yarn by three-ingredientasynchronous/synchronous drafting is disclosed, comprising:

1) a drafting and twisting system includes a first stage drafting unitand a successive second stage drafting unit;

2) the first stage drafting unit includes a combination of back rollers11 and a middle roller 3; The combination of back rollers has threerotational degrees of freedom and includes a first back roller 5, asecond back roller 7, a third back roller 9, which are set abreast on asame back roller shaft. The second stage synchronous drafting unitincludes a front roller 1 and the middle roller 3. 4 is the top rollerof middle roller 3. 6, 8, 10 are the top rollers of three back rollersrespectively. 2 is the top roller of front roller 1. 14 and 13 are thewinding device and guider roller respectively. 15 is the yarn Y. O₁,O′₁,O₂,O₂′, O₃,O₃′ respectively refer to axis lines of back rollers, themiddle roller and the front roller.

The first back roller, the second back roller, the third back rollermove at the speeds V_(h1), V_(h2), and V_(h3) respectively. The middleroller rotates at the speed V_(z). The second stage synchronous draftingunit includes a front roller and the middle roller. The front rollerrotates at the surface linear speed V_(q).

FIG. 2 shows a three-nested combination of back rollers with threerotational degrees of freedom. The three movable back rollers 5, 7, 9are respectively driven by a core shaft and pulleys 16, 22 and 17.

FIG. 4 illustrates the yarn route of the two-stage drafting. During theprocess of spinning, the three roving yarns are fed in parallel into thecorresponding independently driven first stage drafting mechanism to beasynchronously drafted, and synchronously drafted and integrated by thesecond stage drafting mechanism, and then twisted to form a yarn Y.Dynamical change of blend ratio and yarn density can be controlledexactly by the first-stage asynchronous drafting. The yarn density canbe controlled by the second-stage drafting. Thus the yarn can beproduces with much fine mixing and low breaking ration.

As figured out by FIG. 5 the control system mainly includes a PLCprogrammable controller, a servo driver, a servo motor, RecommendedStandard (RS) 232 serial port, RS 485 serial port, etc. PLC programmablecontroller controls rollers, ring rails and spindles by servo motorwhich is controlled by servo driver.

Assuming the linear densities of a first roving yarn ingredient, asecond roving yarn ingredient, a third roving yarn ingredient drafted bythe first back roller, the second back roller, the third back roller arerespectively ρ₁, ρ₂, and ρ₃, the linear density of the yarn Y draftedand twisted by the front roller is ρ_(y).

$\begin{matrix}{\rho_{y} = {\frac{1}{V_{q}}\left( {{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}} \right)}} & (1)\end{matrix}$

The blending ratios of the first roving yarn ingredient, the secondroving yarn ingredient, and the third roving yarn ingredient arerespectively k₁, k₂, and k₃.

$k_{1} = {\frac{\rho_{1}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{1}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{1}*V_{h\; 1}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{2} = {\frac{\rho_{2}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{2}*V_{h\; 2}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{3} = {\frac{\rho_{3}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{3}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{3}*V_{h\; 3}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$

3) Keeping the ratio of linear speeds of the front roller and the middleroller V_(q)/V_(z) constant, the speeds of the front roller and themiddle roller depend on reference linear density of the yarn;

4) The linear density of yarn Y or/and blending ratio can be dynamicallyadjusted on line, by adjusting the rotation rates of the first backroller, the second back roller, the third back roller.

5) Further, the blending ratios of the first roving yarn ingredient, thesecond roving yarn ingredient, the third roving yarn ingredient are setrespectively as k₁, k₂, and k₃. The ratios of blending ratios of theyarn Y are respectively K₁, and K₂.

$K_{1} = {\frac{k_{1}}{k_{2}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{2}V_{h\; 2}}}$$K_{2} = {\frac{k_{1}}{k_{3}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{3}V_{h\; 3}}}$

Linear density of yarn Y is

$\rho_{y} = \frac{{V_{h\; 1}*\rho_{1}} + {V_{h2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}{V_{q}}$

then a surface linear speed of the back roller 1:

$V_{h\; 1} = \frac{\rho_{y}V_{q}}{\rho_{1}\left( {1 + \frac{1}{K_{1}} + \frac{1}{K_{2}}} \right)}$

a surface linear speed of the back roller 2:

$V_{h\; 2} = \frac{\rho_{y}V_{q}}{\rho_{2}\left( {1 + K_{1} + \frac{K_{1}}{K_{2}}} \right)}$

a surface linear speed of the back roller 3:

$V_{h\; 3} = \frac{\rho_{y}V_{q}}{\rho_{3}\left( {1 + K_{2} + \frac{K_{2}}{K_{1}}} \right)}$

wherein ρ₁, ρ₂ and ρ₃ are constants, and K_(i) and ρ_(y) are functionschanging with time t.

6) Further, let ρ₁=ρ₂=ρ₃=ρ, then:

(1) change the speed of any one of the first back roller, the secondback roller, and the third back roller, and keep the speeds of the othertwo backer rollers unchanged. The yarn ingredient and the linear densitythereof of the yarn Y drafted by this back roller change accordingly.The linear density ρ′_(y) of the yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 2}}} \right)\mspace{14mu}{or}}}$${\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 1}}} \right)}}}\mspace{11mu}$

wherein Δρ_(y) is a linear density change of the yarn, ΔV_(h1), ΔV_(h2)and ΔV_(h3) is a speed change of the first back roller, the second backroller, and the third back roller respectively.

(2) change the speeds of any two back rollers of the first back roller,the second back roller, and the third back roller, and keep the speedsof the other backer roller unchanged. The yarn ingredients of the yarn Ydrafted by these any two back rollers and the linear densities thereofchange accordingly. The linear density ρ′_(y) of yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack}}$

(3) change the speeds of three back rollers of the first back roller,the second back roller, and the third back roller simultaneously. Theyarn ingredients of the yarn Y drafted by these three back rollers andthe linear densities thereof change accordingly. The linear densityρ′_(y) of the yarn Y is adjusted as:

${\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack}}}\;$

7) Further, change the speeds of the first back roller, the second backroller, and the third back roller, and make the speed of any of backrollers equal to zero, while the speeds of the other two backer rollersunequal to zero. The yarn ingredient of the yarn Y drafted by the anyone of back rollers is thus discontinuous, while the other two yarningredients are continuous. The linear density ρ′_(y) of yarn Y isadjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {{\Delta\; V_{h\; 3}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$${\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + V_{h\; 2}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}\mspace{14mu}$

wherein T₁ and T₂ are time points, and t is a time variable.

8) Further, change the speeds of the first back roller, the second backroller, and the third back roller, make the speeds of any two backrollers equal to zero successively, while the speeds of the other onebacker rollers unequal to zero. The yarn ingredients of the yarn Ydrafted by the any two back rollers are thus discontinuous, while theother yarn ingredients are continuous. The linear density ρ′_(y) of theyarn Y is adjusted as:

(1) When the first back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {{\Delta\; V_{h\; 3}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + V_{h\; 1}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}\;$$\mspace{85mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + V_{h\; 1}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$

wherein T₃ is time points, and T₁≤T₂≤T₃.

(2) When the second back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + V_{h\; 2}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{76mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + V_{h\; 2}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{2} \leq t \leq T_{3}} \right).}}}}$

(3) When the third back roller is unequal to zero

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + V_{h\; 2}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t} \middle| {\leq T_{2}} \right)}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$

9) further change the speeds of the first back roller, the second backroller, and the third back roller, make the speeds of any two backrollers equal to zero simultaneously, while the speeds of the other onebacker rollers unequal to zero. The yarn ingredients of the yarn Ydrafted by the any two back rollers are thus discontinuous, while theother one yarn ingredients are continuous. The linear density ρ′_(y) ofthe yarn Y is adjusted as:

$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + V_{h\; 1}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{79mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{1} \leq t \leq T_{2}} \right).}}}}$

10) Further, change the speeds of the first back roller, the second backroller, and the third back roller, and keep

V_(h1)*ρ₁+V_(h2)*ρ₂+V_(h3)*ρ₃=constant

and ρ₁=ρ₂=ρ₃=ρ,

then the linear density of the yarn Y is thus fixed while the blendingratios of the ingredients thereof change; the blending ratios of thefirst yarn ingredient, the second yarn ingredient, and the third yarningredient are k₁, k₂, k₃.

$k_{1} = \frac{V_{h\; 1} + {\Delta\; V_{h\; 1}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{2} = \frac{V_{h\; 2} + {\Delta\; V_{h\; 2}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{3} = \frac{V_{h\; 3} + {\Delta\; V_{h\; 3}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$

Embodiment 2

The method of this embodiment is substantially the same as Embodiment 1,and the differences are:

1) according to the set blending ratio and/or linear density, divide theyarn Y into n segments. The linear density and blending ratio of eachsegment of the yarn Y are the same, while the linear densities andblending ratios of the adjacent segments are different. When draftingthe segment i of the yarn Y, the linear speeds of the first back roller,the second back roller, the third back roller are V_(h1i), V_(h2i),V_(h3i), wherein i∈(1, 2, . . . , n) The first roving yarn ingredient,the second roving yarn ingredient, the third roving yarn ingredientingredient are two-stage drafted and twisted to form segment i of theyarn Y, and the blending ratios k_(1i), k_(2i) and k_(3i) thereof areexpressed as below:

$\begin{matrix}{k_{11} = \frac{\rho_{1}*\Delta\; V_{h\; 11}}{{\rho_{1}*V_{h\; 11}} + {\rho_{2}*V_{h\; 21}} + {\rho_{3}*V_{h\; 31}}}} & (2) \\{k_{21} = \frac{\rho_{2}*\Delta\; V_{h\; 21}}{{\rho_{1}*V_{h\; 11}} + {\rho_{2}*V_{h\; 21}} + {\rho_{3}*V_{h\; 31}}}} & (3) \\{k_{31} = \frac{\rho_{3}*\Delta\; V_{h\; 31}}{{\rho_{1}*V_{h\; 11}} + {\rho_{2}*V_{h\; 21}} + {\rho_{3}*V_{h\; 31}}}} & (4)\end{matrix}$

the linear density of segment i of yard Y is:

$\begin{matrix}{\rho_{yi} = {{\frac{V_{z}}{V_{q}}*\left( {{\frac{V_{h\; 11}}{V_{x}}*\rho_{1}} + {\frac{V_{h\; 21}}{V_{\square}}\rho_{2}} + {\frac{V_{\square}}{V_{x}}\rho_{3}}} \right)} = {\frac{1}{e_{q}}*\left( {{\frac{V_{h\; 11}}{V_{x}}*\rho_{1}} + {\frac{V_{h\; 21}}{V_{x}}\rho_{2}} + {\frac{V_{h\; 31}}{V_{x}}\rho_{3}}} \right)}}} & (5)\end{matrix}$

wherein

$e_{q} = \frac{V_{q}}{V_{z}}$is the two-stage arming ratio;

2) Take the segment with the lowest density as a reference segment,whose reference linear density is ρ₀. The reference linear speeds of thefirst back roller, the second back roller, the third back roller forthis segment are respectively V_(h10), V_(h20), V_(h30); and thereference blending ratios of the first roving yarn ingredient, thesecond roving yarn ingredient, the third roving yarn ingredient for thissegment are respectively k₁₀, k₂₀, k₃₀,

Keep the linear speed of the middle roller constant, andV _(z) =V _(h10) +V _(h20) +V _(h30)  (6);also keep two-stage drafting ratio

$e_{q} = \frac{V_{q}}{V_{z}}$constant;

wherein the reference linear speeds of the first back roller, the secondback roller, the third back roller for this segment are respectivelyV_(h10), V_(h20), V_(h30), which can be predetermined according to thematerial, reference linear density ρ₀ and reference blending ratios k₁₀,k₂₀, k₃₀ of the first roving yarn ingredient, the second roving yarningredient, the third roving yarn ingredient.

3) When the segment i of the yarn Y is drafted and blended, on thepremise of known set linear density ρ_(yi) and blending ratios k_(1i),k_(2i), k_(3i), the linear speeds V_(h1i), V_(h2i), V_(h3i), of thefirst back roller, the second back roller, the third back roller arecalculated according to Equations (2)-(6);

4) Based on the reference linear speeds V_(h10), V_(h20), V_(h30) forthe reference segment, increase or decrease the rotation rates of thefirst back roller, the second back roller, the third back roller todynamically adjust the linear density or/and blending ratio for thesegment i of the yarn Y.

5) Further, let ρ₁=ρ₂=ρ₃=ρ

then Equation (5) can be simplified as

$\begin{matrix}{{\rho_{yi} = {\frac{\rho}{e_{q}}*\frac{V_{h\; 11} + V_{h\; 21} + V_{h\; 31}}{V_{1}}}};} & (7)\end{matrix}$

According to Equations (2)-(4) and (6)-(7), the linear speeds V_(h1i),V_(h2i), V_(h3i) of the first back roller, the second back roller, thethird back roller are calculated; based on the reference linear speedsV_(h10), V_(h20), V_(h30), the rotation rates of the first back roller,the second back roller, the third back roller are increased or decreasedto reach the preset linear density and blending ratio for the segment iof yarn Y.

6) Further, at the moment of switching the segment i−1 to the segment iof yarn Y, let the linear density of the yarn Y increase by dynamicincrement Δρ_(yi), i.e., thickness change Δρ_(yi), on the basis ofreference linear density; and thus the first back roller, the secondback roller, the third back roller have corresponding increments on thebasis of the reference linear speed, i.e., when(V_(h10)+V_(h20)+V_(h30))→(V_(h10)+ΔV_(h1i)+V_(h20)+ΔV_(h2i)+V_(h30)+ΔV_(h3i)),the linear density increment of yarn Y is:

${\Delta\;\rho_{yi}} = {\frac{\rho}{e_{q} \times V_{z}}*{\left( {{\Delta\; V_{h\; 11}} + {\Delta\; V_{h\; 21}} + {\Delta\; V_{h\; 31}}} \right).}}$

Then the linear density ρ_(yi) of the yarn Y is expressed as

$\begin{matrix}{\rho_{y\; i} = {{\rho_{y\; 0} + {\Delta\;\rho_{yi}}} = {\rho_{y\; 0} + {\frac{{\Delta\; V_{h\; 1\; i}} + {\Delta\; V_{h\; 2\; i}} + {\Delta\; V_{h\; 3\; i}}}{V_{z}}*{\frac{\rho}{e_{q}}.}}}}} & (8)\end{matrix}$

Let ΔV₁=ΔV_(h1i)+ΔV_(h2i)+ΔV_(h3i),

then Equation (8) is simplified as:

$\begin{matrix}{\rho_{y\; i} = {\rho_{y\; 0} + {\frac{\Delta\; V_{1}}{V_{z}}*{\frac{\rho}{e_{q}}.}}}} & (9)\end{matrix}$

The linear density of yarn Y can be adjusted by controlling the sum ofthe linear speed increments ΔV_(i) of the first back roller, the secondback roller, the third back roller.

7) Further, let ρ₁=ρ₂=ρ₃=ρ

at the moment of switching the segment i−1 to the segment i of the yarnY, the blending ratios of the yarn Yin Equations (2)-(3) can besimplified as:

$\begin{matrix}{k_{1\; i} = \frac{V_{h\; 10} + {\Delta\; V_{h\; 1i}}}{V_{z} + {\Delta\; V_{i}}}} & (10) \\{k_{2\; i} = \frac{V_{h\; 20} + {\Delta\; V_{h\; 2i}}}{V_{z} + {\Delta\; V_{i}}}} & (11) \\{k_{3\; i} = \frac{V_{h\; 30} + {\Delta\; V_{h\; 3i}}}{V_{z} + {\Delta\; V_{i}}}} & (12)\end{matrix}$

The blending ratios of the yarn Y can be adjusted by controlling thelinear speed increments of the first back roller, the second backroller, the third back roller;

whereinΔV _(h1i) =k _(1i)*(V _(Z) +ΔV _(i))−V _(h10)ΔV _(h2i) =k _(2i)*(V _(Z) +ΔV _(i))−V _(h20)ΔV _(h3i) =k _(3i)*(V _(Z) +ΔV _(i))−V _(h30).

8) Further, let V_(h1i)*ρ₁+V_(h2i)*ρ₂+V_(h3i)*ρ₃=H

and H is a constant, then ΔV_(i) is constantly equal to zero, and thusthe linear density is unchanged when the blending ratios of the yarn Yare adjusted.

9) Further, let any one to two of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equalto zero, while the remaining ones are not zero, then the one to tworoving yarn ingredients can be changed while the other roving yarningredients are unchanged. The adjusted blending ratio are:

$k_{ki} = \frac{V_{{hk}\; 0} + {\Delta\; V_{hki}}}{V_{z} + {\Delta\; V_{i}}}$$k_{ji} = \frac{V_{{hj}\; 0}}{V_{z} + {\Delta\; V_{i}}}$

wherein k, j∈(1, 2, 3), and k≠j.

10) Further, let none of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equal to zero,then the proportion of the three roving yarn ingredients in the yarn Ymay be changed.

11) Further, let any one to two of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equalto zero, while the remaining ones are not zero, then the one to tworoving yarn ingredients of the segment i of the yarn Y may bediscontinuous.

Embodiment 3

The method of dynamically configuring linear density and blending ratioof a yarn by three-ingredient asynchronous drafting disclosed in thisembodiment is substantially the same as Embodiment 2, and thedifferences are:

Set the initial linear speeds of the first back roller, a second backroller, a third back roller as V_(h10), V_(h20), V_(h30); the initiallinear speed of the middle roller V_(z0)=V_(h10)+V_(h20)+V_(h30)

In addition, set V_(Zi)=V_(h1(i-1))+V_(h2(i-1))+V_(h3(i-1)),

and let the two-stage drafting ratio

$e_{qi} = \frac{v_{qi}}{v_{zi}}$constantly be equal to the set value e_(q);

When drafting and blending the segment i of the yarn Y, take the lineardensity and the blending ratio of the segment i−1 as a reference lineardensity and a reference blending ratio of segment i. On the premise ofthe known set linear density ρ_(yi) and blending ratios k_(1i), k_(2i),k_(3i), the linear speeds V_(h1i), V_(h2i), V_(h3i) of a first backroller, a second back roller, a third back roller are calculated.

On the basis of the segment i−1, the rotation rates of the first backroller the second back roller and the third back roller are adjusted todynamically regulate the linear density or/and blending ratio of segmenti of the yarn Y on line.

In the method, V_(Zi)=V_(h1(i-1))+V_(h2(i-1))+V_(h3(i-1)) and thetwo-stage drafting ratio is constant, and thus the speeds of the middleroller and the front roller are continually adjusted with the speeds ofthe back rollers, to avoid a substantial change of the drafting ratio ofthe yarn resulted from untimely adjusted speeds of the middle roller andthe front roller as opposed to a relatively large speed adjustment ofthe combination of the back rollers, and effectively prevent yarnbreakage.

In addition, the operating speed of each roller is recorded in real timeby a computer or other intellectual control unit, and thus the speeds ofthe middle roller and the front roller in the next step can beautomatically calculated if the current speeds of the back rollers areknown. The speed increments/decrements of the combination of the backrollers are calculated quickly with the above equations and models, toadjust the set blending ratio and linear density more easily andaccurately.

TABLE 3 Parameter comparison between asynchronous drafting andsynchronous drafting (taking 18.45tex cotton yarn as an example)Synchronous drafting Synchronous drafting Asynchronous drafting fordouble ingredients for double ingredients for three ingredientsSynchronous drafting spinning spinning spinning for single ingredientIngredi- Ingredi- Ingredi- Ingredi- Ingredi- Ingredi- Ingredi- spinningent 1 ent 2 ent 1 ent 2 ent 1 ent 2 ent 3 Roving yarn 5.0 5.0 5.0 5.05.0 5.0 5.0 5.0 weight (g/5 in) Back area 1.1-1.3 1.1-1.3 1.1-1.31.1-1.3 1.1-1.3 1.1-1.3 3°(k1 + 3°(k1 + 3°(k1 + drafting k2 + 3)/k1 k2 +k3)/k2 k2 + k3)/k3 ratio Changes with Changes with Changes with theblending the blending the blending ratio ratio ratio Front area24.6-20.8 32.7 49.2-41.6 49.2-41.6 45.4 45.4 81.6 81.6 81.6 draftingratio Back roller unchanged changed unchanged changed AsynchronousAsynchronous Asynchronous speed change change change Middle rollerunchanged unchanged unchanged unchanged unchanged speed Front rollerunchanged unchanged unchanged unchanged unchanged speed Average 18.4518.45 18.45 18.45 18.45 spinning number (tex) Linear speed invariableLimitedly invariable Limitedly Variable, adjustable variable variablevariable Blending invariable invariable invariable Limitedly Variable,adjustable ratio variable variable Linear speed invariable invariableinvariable Limitedly Variable, adjustable and blending variable ratioboth variable Spinning Even yarn Slub yarn Even yarn Limited Even yarnEven yarn Even yarn Even yarn effect segmented Any Any Any Any colorblending blending blending blending Limited ratio ratio ratio ratio slubyarn Color- Segment- Segment- slub yarn blended color color yarn blendedblended yarn yarn

Several preferable embodiments are described, in combination with theaccompanying drawings. However, the invention is not intended to belimited herein. Any improvements and/or modifications by the skilled inthe art, without departing from the spirit of the invention, would fallwithin protection scope of the invention.

What is claimed is:
 1. A method of dynamically configuring a lineardensity and a blending ratio of a yarn by three-ingredientasynchronous/synchronous drafting, comprising: providing an actuatingmechanism, wherein the actuating mechanism includes a three-ingredientasynchronous/synchronous two-stage drafting mechanism, a twistingmechanism and a winding mechanism; wherein the three-ingredientasynchronous/synchronous two-stage drafting mechanism includes a firststage asynchronous drafting unit and a successive second stagesynchronous drafting unit; providing a combination of a plurality ofback roller and a middle roller included by the first stage asynchronousdrafting unit; wherein the combination of back rollers has threerotational degrees of freedom and includes a first back roller, a secondback roller, a third back roller, which are set abreast on a same backroller shaft; the first back roller, the second back roller, the thirdback roller move at the speeds V_(h1), V_(h2), and V_(h3) respectively;the middle roller rotates at the speed V_(z); the second stagesynchronous drafting unit includes a front roller and the middle roller;the front roller rotates at the surface linear speed V_(q); assuming thelinear densities of a first roving yarn ingredient, a second roving yarningredient, a third roving yarn ingredient drafted by the first backroller, the second back roller, the third back roller are respectivelyρ₁, ρ₂, and ρ₃, the linear density of the yarn Y drafted and twisted bythe front roller is ρ_(y); $\begin{matrix}{\rho_{y} = {\frac{1}{V_{q}}\left( {{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}} \right)}} & (1)\end{matrix}$ the blending ratios of the first roving yarn ingredient,the second roving yarn ingredient, and the third roving yarn ingredientare respectively k₁, k₂, and k₃;$k_{1} = {\frac{\rho_{1}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{1}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{1}*V_{h\; 1}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{2} = {\frac{\rho_{2}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{2}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{2}*V_{h\; 2}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$$k_{3} = {\frac{\rho_{3}^{''}}{\rho_{1}^{''} + \rho_{2}^{''} + \rho_{3}^{''}} = {\frac{\rho_{3}^{\prime}}{\rho_{1}^{\prime} + \rho_{2}^{\prime} + \rho_{3}^{\prime}} = \frac{\rho_{3}*V_{h\; 3}}{{\rho_{1}*V_{h\; 1}} + {\rho_{2}*V_{h\; 2}} + {\rho_{3}*V_{h\; 3}}}}}$keeping the ratio of linear speeds of the front roller and the middleroller V_(q)/V_(z) constant, the speeds of the front roller and themiddle roller depend on reference linear density of the yarn; adjustingthe rotation rates of the first back roller, the second back roller, thethird back roller, so as to dynamically adjust the linear density and ablending ratio K of a yarn Y online.
 2. The method of claim 1, whereinaccording to the changes of the blending ratio K of the yarn Y with atime t, and the changes of the linear density ρ_(y) of the yarn Y withthe time t, the changes of surface linear speeds of the first backroller, the second back roller, the third back roller are derived;blending ratios of the first roving yarn ingredient, the second rovingyarn ingredient, the third roving yarn ingredient are set respectivelyas k₁, k₂, and k₃; a plurality of blending ratios of the yarn Y arerespectively K₁, and K₂:$K_{1} = {\frac{k_{1}}{k_{2}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{2}V_{h\; 2}^{\prime}}}$$K_{2} = {\frac{k_{1}}{k_{3}} = \frac{\rho_{1}V_{h\; 1}}{\rho_{3}V_{h\; 3}}}$a linear density of yarn Y is$\rho_{y} = \frac{{V_{h\; 1}*\rho_{1}} + {V_{h\; 2}*\rho_{2}} + {V_{h\; 3}*\rho_{3}}}{V_{q}}$then a surface linear speed of the first back roller:$V_{h\; 1} = \frac{\rho_{y}V_{q}}{\rho_{1}\left( {1 + \frac{1}{K_{1}} + \frac{1}{K_{2}}} \right)}$a surface linear speed of the second back roller:$V_{h\; 2} = \frac{\rho_{y}V_{q}}{\rho_{2}\left( {1 + K_{1} + \frac{K_{1}}{K_{2}}} \right)}$a surface linear speed of the third back roller:$V_{h\; 3} = \frac{\rho_{y}V_{q}}{\rho_{3}\left( {1 + K_{2} + \frac{K_{2}}{K_{1}}} \right)}$wherein ρ₁, ρ₂, and ρ₃ are constants, and K_(i) and ρ_(y) are functionschanging with the time t.
 3. The method of claim 1, wherein ifρ₁=ρ₂=ρ₃=ρ, then: 1) changing the speed of any one of the first backroller, the second back roller, and the third back roller, and keepingthe speeds of the other two back rollers unchanged; the yarn ingredientand the linear density thereof of the yarn Y drafted by this back rollerchange accordingly; the linear density ρ′_(y) of the yarn Y is adjustedas:$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 2}}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left( {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + {\Delta\; V_{h\; 1}}} \right)}}$wherein Δρ_(y) is a linear density change of the yarn, ΔV_(h1), ΔV_(h2)and ΔV_(h3) is a speed change of the first back roller, the second backroller, and the third back roller respectively; 2) changing the speedsof any two back rollers of the first back roller, the second backroller, and the third back roller, and keeping the speed of the otherback roller unchanged; the yarn ingredients of the yarn Y drafted bythese any two back rollers and the linear densities thereof changeaccordingly; the linear density ρ′_(y) of yarn Y is adjusted as:$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack}}$3) changing the speeds of three back rollers of the first back roller,the second back roller, and the third back roller simultaneously; theyarn ingredients of the yarn Y drafted by these any three back rollersand the linear densities thereof change accordingly; the linear densityρ′_(y) of the yarn Y is adjusted as:$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*{\left\lbrack {V_{h\; 1} + V_{h\; 2} + V_{h\; 3} + \left( {{\Delta\; V_{h\; 1}} + {\Delta\; V_{h\; 2}} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack.}}}$4. The method of claim 3, wherein changing the speeds of the first backroller, the second back roller, and the third back roller, and makingthe speed of any of back rollers equal to zero, while the speeds of theother two back rollers unequal to zero; the yarn ingredient of the yarnY drafted by the any one of back rollers is thus discontinuous, whilethe other two yarn ingredients are continuous; the linear density ρ′_(y)of yarn Y is adjusted as:$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$wherein T₁ and T₂ are time points, and t is a time variable.
 5. Themethod of claim 3, wherein changing the speeds of the first back roller,the second back roller, and the third back roller, making the speeds ofany two back rollers equal to zero successively, while the speeds of theother one back rollers unequal to zero; the yarn ingredients of the yarnY drafted by the any two back rollers are thus discontinuous, while theother yarn ingredients are continuous; the linear density ρ′_(y) of theyarn Y is adjusted as: when the first back roller is unequal to zero$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$wherein T₃ is time points, and T₁≤T₂≤T₃; when the second back roller isunequal to zero$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)}}}$when the third back roller is unequal to zero$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}\left( {T_{2} \leq t \leq T_{3}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{2} \leq t \leq T_{3}} \right).}}}}$6. The method of claim 3, wherein further changing the speeds of thefirst back roller, the second back roller, and the third back roller,making the speeds of any two back rollers equal to zero simultaneously,while the speeds of the other one back rollers unequal to zero; the yarningredients of the yarn Y drafted by the any two back rollers are thusdiscontinuous, while the other one yarn ingredients are continuous; thelinear density ρ′_(y) of the yarn Y is adjusted as:$\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack {\left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) + \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) + \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right)} \right\rbrack\mspace{14mu}\left( {0 \leq t \leq T_{1}} \right)}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 1} + {\Delta\; V_{h\; 1}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 2} + {\Delta\; V_{h\; 2}}} \right) \right\rbrack\mspace{14mu}\left( {T_{1} \leq t \leq T_{2}} \right)\mspace{14mu}{or}}}}$$\mspace{20mu}{\rho_{y}^{\prime} = {{\rho_{y} + {\Delta\;\rho_{y}}} = {\frac{\rho}{V_{q}}*\left\lbrack \left( {V_{h\; 3} + {\Delta\; V_{h\; 3}}} \right) \right\rbrack\mspace{14mu}{\left( {T_{1} \leq t \leq T_{2}} \right).}}}}$7. The method of claim 3, wherein changing the speeds of the first backroller, the second back roller, and the third back roller, and keepingV_(h1)*ρ₁+V_(h2)*ρ₂+V_(h3)*ρ₃=constant and ρ₁=ρ₂=ρ₃=ρ, then the lineardensity of the yarn Y is thus fixed while the blending ratios of theingredients thereof change; the blending ratios of the first yarningredient, the second yarn ingredient, and the third yarn ingredientare k₁, k₂, k₃:$k_{1} = \frac{V_{h\; 1} + {\Delta\; V_{h\; 1}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{2} = \frac{V_{h\; 2} + {\Delta\; V_{h\; 2}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}$$k_{3} = {\frac{V_{h\; 3} + {\Delta\; V_{h\; 3}}}{V_{h\; 1} + {\Delta\; V_{h\; 1}} + V_{h\; 2} + {\Delta\; V_{h\; 2}} + V_{h\; 3} + {\Delta\; V_{h\; 3}}}.}$8. The method of claim 1, wherein further, according to the set blendingratio and/or linear density, divide the yarn Y into n segments; thelinear density and blending ratio of each segment of the yarn Y are thesame, while the linear densities and blending ratios of the adjacentsegments are different; when drafting the segment i of the yarn Y, thelinear speeds of the first back roller, the second back roller, thethird back roller are V_(h1i), V_(h2i), V_(h3i), wherein i∈(1, 2, . . ., n); the first roving yarn ingredient, the second roving yarningredient, the third roving yarn ingredient are two-stage drafted andtwisted to form segment i of the yarn Y, and the blending ratios k_(1i),k_(2i) and k_(3i) thereof are expressed as below: $\begin{matrix}{k_{1\; i} = \frac{\rho_{1}*V_{h\; 1\; i}}{{\rho_{1}*V_{h\; 1\; i}} + {\rho_{2}*V_{h\; 2\; i}} + {\rho_{3}*V_{h\; 3\; i}}}} & (2) \\{k_{2\; i} = \frac{\rho_{2}*V_{h\; 2\; i}}{{\rho_{1}*V_{h\; 1\; i}} + {\rho_{2}*V_{h\; 2\; i}} + {\rho_{3}*V_{h\; 3\; i}}}} & (3) \\{k_{3\; i} = \frac{\rho_{3}*V_{h\; 3\; i}}{{\rho_{1}*V_{h\; 1\; i}} + {\rho_{2}*V_{h\; 2\; i}} + {\rho_{3}*V_{h\; 3\; i}}}} & (4)\end{matrix}$ the linear density of segment i of yarn Y is:$\begin{matrix}{\rho_{yi} = {{\frac{V_{z}}{V_{q}}*\left( {{\frac{V_{h\; 1\; i}}{V_{z}}*\rho_{1}} + {\frac{V_{h\; 2\; i}}{V_{z}}\rho_{2}} + {\frac{V_{h\; 3i}}{V_{z}}\rho_{3}}} \right)} = {\frac{1}{e_{q}}*\left( {{\frac{V_{h\; 1\; i}}{V_{z}}*\rho_{1}} + {\frac{V_{h\; 2\; i}}{V_{z}}\rho_{2}} + {\frac{V_{h\; 3i}}{V_{z}}\rho_{3}}} \right)}}} & (5)\end{matrix}$ wherein $e_{q} = \frac{v_{q}}{v_{z}}$ is the two-stagedrafting ratio; (1) take the segment with the lowest density as areference segment, whose reference linear density is ρ₀; the referencelinear speeds of the first back roller, the second back roller, thethird back roller for this segment are respectively V_(h10), V_(h20),V_(h30); and the reference blending ratios of the first roving yarningredient, the second roving yarn ingredient, the third roving yarningredient for this segment are respectively k₁₀, k₂₀, k₃₀; keep thelinear speed of the middle roller constant, andV _(z) =V _(h10) +V _(h20) +V _(h30)  (6); (2) also keep two-stagedrafting ratio $e_{q} = \frac{v_{q}}{v_{z}}$ constant; wherein thereference linear speeds of the first back roller, the second backroller, the third back roller for this segment are respectively V_(h10),V_(h20), V_(h30), which are predetermined according to the material,reference linear density ρ₀ and reference blending ratios k₁₀, k₂₀, k₃₀of the first roving yarn ingredient, the second roving yarn ingredient,the third roving yarn ingredient; (3) when the segment i of the yarn Yis drafted and blended, on the premise of known set linear densityρ_(yi) and blending ratios k_(1i), k_(2i), k_(3i), the linear speedsV_(h1i), V_(h2i), V_(h3i), of the first back roller, the second backroller, the third back roller are calculated according to equations(2)-(6); (4) based on the reference linear speeds V_(h10), V_(h20),V_(h30) for the reference segment, increase or decrease the rotationrates of the first back roller, the second back roller, the third backroller to dynamically adjust the linear density or/and blending ratiofor the segment i of the yarn Y.
 9. The method of claim 8, wherein letρ₁=ρ₂=ρ₃=ρ the equation (5) is simplified as $\begin{matrix}{{\rho_{y\; i} = {\frac{\rho}{e_{q}}*\frac{V_{h\; 1i} + V_{h\; 2i} + V_{h\; 3i}}{V_{z}}}};} & (7)\end{matrix}$ according to equations (2)-(4) and (6)-(7), the linearspeeds V_(h1i), V_(h2i), V_(h3i) of the first back roller, the secondback roller, the third back roller are calculated; based on thereference linear speeds V_(h10), V_(h20), V_(h30), the rotation rates ofthe first back roller, the second back roller, the third back roller areincreased or decreased to reach the preset linear density and blendingratio for the segment i of yarn Y.
 10. The method of claim 9, wherein atthe moment of switching the segment i−1 to the segment i of yarn Y, letthe linear density of the yarn Y increase by dynamic increment Δρ_(yi),i.e., thickness change Δρ_(yi), on the basis of reference lineardensity; and thus the first back roller, the second back roller, thethird back roller have corresponding increments on the basis of thereference linear speed, i.e., when(V_(h10)+V_(h20)+V_(h30))→(V_(h10)+ΔV_(h1i)+V_(h20)+ΔV_(h2i)+V_(h30)ΔV_(h3i)) the linear density increment of yarn Y is:${{\Delta\;\rho_{yi}} = {\frac{\rho}{e_{q} + V_{z}}*\left( {{\Delta\; V_{h\; 1i}} + {\Delta\; V_{h\; 2i}} + {\Delta\; V_{h\; 3i}}} \right)}};$then the linear density ρ_(yi) of the yarn Y is expressed as$\begin{matrix}{{\rho_{yi} = {{\rho_{y\; 0} + {\Delta\;\rho_{yi}}} = {\rho_{y\; 0} + {\frac{{\Delta\; V_{h\; 1i}} + {\Delta\; V_{h\; 2i}} + {\Delta\; V_{h\; 3i}}}{V_{z}}*\frac{\rho}{e_{q}}}}}};} & (8)\end{matrix}$ let ΔV₁=ΔV_(h1i)+ΔV_(h2i)+ΔV_(h3i); then equation (8) issimplified as: $\begin{matrix}{{\rho_{yi} = {\rho_{y\; 0} + {\frac{\Delta\; V_{1}}{V_{z}}*\frac{\rho}{e_{q}}}}};} & (9)\end{matrix}$ the linear density of yarn Y is adjusted by controllingthe sum of the linear speed increments ΔV_(i) of the first back roller,the second back roller, the third back roller.
 11. The method of claim10, wherein let ρ₁=ρ₂=ρ₃=ρ at the moment of switching the segment i−1 tothe segment i of the yarn Y, the blending ratios of the yarn Y inequations (2)-(4) are simplified as: $\begin{matrix}{k_{1\; i} = \frac{V_{h\; 10} + {\Delta\; V_{h\; 1i}}}{V_{z} + {\Delta\; V_{i}}}} & (10) \\{k_{2\; i} = \frac{V_{h\; 20} + {\Delta\; V_{h\; 2i}}}{V_{z} + {\Delta\; V_{i}}}} & (11) \\{{k_{3\; i} = \frac{V_{h\; 30} + {\Delta\; V_{h\; 3i}}}{V_{z} + {\Delta\; V_{i}}}};} & (12)\end{matrix}$ the blending ratios of the yarn Y are adjusted bycontrolling the linear speed increments of the first back roller, thesecond back roller, the third back roller; whereinΔV _(h1i) =k _(1i)*(V _(Z) +ΔV _(i))−V _(h10)ΔV _(h2i) =k _(2i)*(V _(Z) +ΔV _(i))−V _(h20)ΔV _(h3i) =k _(3i)*(V _(Z) +ΔV _(i))−V _(h30).
 12. The method of claim11, wherein let V_(h1i)*ρ₁+V_(h2i)*ρ₂+V_(h3i)*ρ₃=H and H is a constant,then ΔV_(i) is constantly equal to zero, and thus the linear density isunchanged when the blending ratios of the yarn Y are adjusted.
 13. Themethod of claim 11, wherein let any one to two of ΔV_(h1i), ΔV_(h2i),ΔV_(h3i) be equal to zero, while the remaining ones are not zero, thenthe one to two roving yarn ingredients are changed while the otherroving yarn ingredients are unchanged; the adjusted blending ratios are:$k_{ki} = \frac{V_{{hk}\; 0} + {\Delta\; V_{hki}}}{V_{z} + {\Delta\; V_{i}}}$$k_{ji} = \frac{V_{{hj}\; 0}}{V_{z} + {\Delta\; V_{i}}}$ wherein k,j∈(1, 2, 3) and k≠j; let none of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equalto zero, then the proportion of the three roving yarn ingredients in theyarn Y is changed.
 14. The method of claim 11, wherein let any one totwo of ΔV_(h1i), ΔV_(h2i), ΔV_(h3i) be equal to zero, while theremaining ones are not zero, then the one to two roving yarn ingredientsof the segment i of the yarn Y are discontinuous.
 15. A device forimplementing a method of dynamically configuring a linear density and ablend ratio of a yarn by three-ingredient asynchronous/synchronousdrafting, comprising: a control system, and an actuating mechanism,wherein the actuating mechanism includes a three-ingredientseparate/integrated asynchronous/synchronous two-stage draftingmechanism, a twisting mechanism and a winding mechanism; the two-stagedrafting mechanism includes a first stage drafting unit and a secondstage drafting unit; the first stage drafting unit includes acombination of back rollers and a middle roller; the combination of backrollers has three rotational degrees of freedom and includes a firstback roller, a second back roller, a third back roller, which are setabreast on a same back roller shaft; the second stage drafting unitincludes a front roller and the middle roller.